July 16, 2015 Chattanooga, Tennessee
5 killed, 3 injured:
A gunman opened fire on two military facilities over seven kilometers apart, killing four Marines and a Navy sailor. The man identified by federal authorities as Mohammod Youssuf Abdulazeez, 24 then drove to a Navy-Marine training centre and opened fire before he was neutralized.
April 2, 2014 Ft. Hood, Texas
3 killed; 16 injured
A gunman at Fort Hood, the scene of a deadly 2009 rampage, kills three people and injures 16 others, according to military officials. The gunman is dead at the scene.
September 16, 2013 Washington, D.C.
12 killed, 3 injured
Aaron Alexis, a Navy contractor and former Navy enlisted man, shoots and kills 12 people and engages police in a firefight throughout the sprawling Washington Navy Yard. Authorities shoot and killed him.
Authorities later show that he had an extensive Navy disciplinary document that included several absences from duty, instances of insubordination and disorderly conduct and several failed inspections. He was still able purchase a rifle and to have a security clearance.
November 5, 2009 Ft. Hood, Texas
13 killed, 32 injured
Maj. Nidal Malik Hasan, an Army psychiatrist, allegedly shoots and kills 13 people and injures 32 others in a rampage at Ft. Hood, where he is based. Authorities allege that Hasan was exchanging emails with Muslim extremists including American-born radical Anwar Awlaki.